import java.util.Scanner;

public class Demo5 {
    public static void SingleDog(int[] arr){
        int i=0;
        int j=0;
        for ( i = 0; i <arr.length ; i++) {
           for(j=i+1;j< arr.length;j++){
               int tmp=j;
               if(arr[i]==arr[j]){
                   j++;
                   break;
               }
               if(j==tmp){
                   System.out.println(arr[i]);
               }
           }
        }
    }
    public static void main(String[] args) {
        int[] arr=new int[3];
        Scanner scanner=new Scanner(System.in);
        for (int i = 0; i < arr.length ; i++) {
            arr[i]=scanner.nextInt();
        }
        SingleDog(arr);
    }
}
